Semiconductor device and display device including the same
A change in electrical characteristics in a semiconductor device including an oxide semiconductor film is inhibited, and the reliability is improved. The semiconductor device includes a gate electrode, a first insulating film over the gate electrode, an oxide semiconductor film over the first insulating film, a source electrode electrically connected to the oxide semiconductor film, a drain electrode electrically connected to the oxide semiconductor film, a second insulating film over the oxide semiconductor film, the source electrode, and the drain electrode, a first metal oxide film over the second insulating film, and a second metal oxide film over the first metal oxide film. The first metal oxide film contains at least one metal element that is the same as a metal element contained in the oxide semiconductor film. The second metal oxide film includes a region where the second metal oxide film and the first metal oxide film are mixed.
1. A method for manufacturing a semiconductor device comprising:
forming a gate electrode;
forming an oxide semiconductor film over the gate electrode;
performing a first heat treatment in an atmosphere of clean dry air after forming the oxide semiconductor film;
forming a silicon oxynitride film comprising a region in contact with the oxide semiconductor film;
forming a first metal oxide film comprising indium over the silicon oxynitride film;
forming a second metal oxide film comprising aluminum over the first metal oxide film;
performing a second heat treatment at a temperature higher than or equal to 150° C. and lower than or equal to 400° C. after forming the second metal oxide film; and
forming a conductive layer over the second metal oxide film.
2. The method for manufacturing a semiconductor device according to claim 1 ,
wherein the oxide semiconductor film comprises In, Zn, and M, and
wherein M is Ti, Ga, Y, Zr, La, Ce, Nd, Sn, or Hf.
3. The method for manufacturing a semiconductor device according to claim 1 ,
wherein the oxide semiconductor film includes a crystal with a size greater than or equal to 1 nm and less than or equal to 10 nm.
4. The method for manufacturing a semiconductor device according to claim 1 , further comprising:
forming a pair of conductive layers over and in contact with the oxide semiconductor film,
wherein the silicon oxynitride film is under the pair of conductive layers.
5. The method for manufacturing a semiconductor device according to claim 4 ,
wherein the pair of conductive layers comprises titanium.
6. A method for manufacturing a semiconductor device comprising:
forming a gate electrode;
forming an oxide semiconductor film over the gate electrode;
performing a first heat treatment in an atmosphere of mixed gases after forming the oxide semiconductor film;
forming a silicon oxynitride film comprising a region in contact with the oxide semiconductor film;
forming a first metal oxide film comprising indium over the silicon oxynitride film;
forming a second metal oxide film comprising aluminum over the first metal oxide film;
performing a second heat treatment at a temperature higher than or equal to 150° C. and lower than or equal to 400° C. after forming the second metal oxide film; and
forming a conductive layer over the second metal oxide film.
7. The method for manufacturing a semiconductor device according to claim 6 ,
wherein the oxide semiconductor film comprises In, Zn, and M, and
wherein M is Ti, Ga, Y, Zr, La, Ce, Nd, Sn, or Hf.
8. The method for manufacturing a semiconductor device according to claim 6 ,
wherein the oxide semiconductor film includes a crystal with a size greater than or equal to 1 nm and less than or equal to 10 nm.
9. The method for manufacturing a semiconductor device according to claim 6 , further comprising:
forming a pair of conductive layers over and in contact with the oxide semiconductor film,
wherein the silicon oxynitride film is under the pair of conductive layers.
10. The method for manufacturing a semiconductor device according to claim 9 ,
wherein the pair of conductive layers comprises titanium.
11. A method for manufacturing a semiconductor device comprising:
forming a gate electrode;
forming an oxide semiconductor film over the gate electrode;
performing a first heat treatment in an atmosphere of clean dry air after forming the oxide semiconductor film;
forming a silicon oxynitride film comprising a region in contact with the oxide semiconductor film;
forming a metal oxide film comprising indium over the silicon oxynitride film;
performing a second heat treatment at a temperature higher than or equal to 150° C. and lower than or equal to 400° C. after forming the metal oxide film; and
forming a conductive layer over the metal oxide film.
12. The method for manufacturing a semiconductor device according to claim 11 ,
wherein the oxide semiconductor film comprises In, Zn, and M, and
wherein M is Ti, Ga, Y, Zr, La, Ce, Nd, Sn, or Hf.
13. The method for manufacturing a semiconductor device according to claim 11 ,
wherein the oxide semiconductor film includes a crystal with a size greater than or equal to 1 nm and less than or equal to 10 nm.
14. The method for manufacturing a semiconductor device according to claim 11 , further comprising:
forming a pair of conductive layers over and in contact with the oxide semiconductor film,
wherein the silicon oxynitride film is under the pair of conductive layers.
15. The method for manufacturing a semiconductor device according to claim 14 ,
wherein the pair of conductive layers comprises titanium.
16. A method for manufacturing a semiconductor device comprising:
forming a gate electrode;
forming an oxide semiconductor film over the gate electrode;
performing a first heat treatment in an atmosphere of mixed gases after forming the oxide semiconductor film;
forming a silicon oxynitride film comprising a region in contact with the oxide semiconductor film;
forming a metal oxide film comprising indium over the silicon oxynitride film;
performing a second heat treatment at a temperature higher than or equal to 150° C. and lower than or equal to 400° C. after forming the metal oxide film; and
forming a conductive layer over the metal oxide film.
17. The method for manufacturing a semiconductor device according to claim 16 ,
wherein the oxide semiconductor film comprises In, Zn, and M, and
wherein M is Ti, Ga, Y, Zr, La, Ce, Nd, Sn, or Hf.
18. The method for manufacturing a semiconductor device according to claim 16 ,
wherein the oxide semiconductor film includes a crystal with a size greater than or equal to 1 nm and less than or equal to 10 nm.
19. The method for manufacturing a semiconductor device according to claim 16 , further comprising:
forming a pair of conductive layers over and in contact with the oxide semiconductor film,
wherein the silicon oxynitride film is under the pair of conductive layers.
20. The method for manufacturing a semiconductor device according to claim 19 ,
wherein the pair of conductive layers comprises titanium.